Materials and Energy Research CenterInternational Journal of Engineering1025-249510119970201Rapidly Varied Unsteady Flow in a Small Scale Dry Bed Model11071166ENY. HassanzadehCivil Engineering, Tabriz UniversityJournal Article19700101In this paper the rapidly varied unsteady flow caused by the failure of a dam in a rectangular dry bed horizontal channel has been studied both theoretically and experimentally. Experiments with dam-break flows in smooth and rough channel have been carried out. Comparisons have been made between measured depth hydrographs at different stations along the channel and analytical solution of Ritter and Dressier in this respect. It is Concluded that the forward zone of flow is highly sensitive to hydraulic resistance, consequently the measured forward wave velocities are markedly lower than those of theoretical one given by Ritter's solution. The roughness elements in the model, simulating the forest trees in prototype valley at downstream of the dam, tends to decrease the flow velocities and to increase flow depths. Finally the comparison showed that the experimental data of rough channel agreed closely with Dressler's solution. Thus, this latest theory may provide more satisfactory results for hydraulic prototypes previsions.https://www.ije.ir/article_71166_e7782384ac0691c38957f59273524b19.pdfMaterials and Energy Research CenterInternational Journal of Engineering1025-249510119970201A Novel Disc-Type Reluctance Motor111871167ENS. Yousefi Azad, Shahid Beheshti UniversityE. AfjeiDepartment of Electrical Engineering, Shahid Beheshti UniversityJournal Article19700101This paper explores the theory and potential of a family of reluctance motors as well as brief review of different types of reluctance motors, motivated by the increased demands for geometric versatility and ruggedness for electric motors. This paper presents a new and novel disc type reluctance motor that has been designed built, tested, and analyzed. The magnetic circuit-based analysis shows an obtainable torque per volume 5 KNm/m3 for the motor which is comparable with other types of electric motors.https://www.ije.ir/article_71167_731d77e2a1be04b29c8e2cd6ead65aa3.pdfMaterials and Energy Research CenterInternational Journal of Engineering1025-249510119970201Wind Energy Estimation for Production of Electricity in Iran192671168ENM. AbbaspourMechanical Engineering, Sharif University of TechnologyF. AtabiMechanical Engineering, Sharif University of TechnologyJournal Article19700101This paper covers the estimation of the average yearly production of an appropriate wind turbine for different locations in Iran. The effects of topography, the influence of obstacles such as buildings and shelters, the collective effects of the surrounding terrain, roughness classifications, and orographic elements such as hills, cliffs, etc., all have been included in the calculations. A full sitting procedure such as availability of power lines, the present and future use of land, etc., have also been taken into account. In order to have an accurate estimation, the selected climatology stations are located no more than 50 km from the site. Information such as number of sites, number and types of typical turbines and their specification, nominal and available power capacity, overall efficiency, and yearly energy production are calculated by the developed mathematical model for 13 different locations. The total nominal power capacity for these sites is close to 5000 MW with an overall efficiency between 33% to 45%. This is equivalent to an annual energy production of 15333 (GWh/yr). The present study shows a promising future for the application of wind energy to produce electricity in Iran.https://www.ije.ir/article_71168_d0de2e296f90baba97b2e4f9413bbf0c.pdfMaterials and Energy Research CenterInternational Journal of Engineering1025-249510119970201Thermal Field Around a Circular Cylinder with Periodic Vortex Shedding273671169END. FotouhiMechanical Engineering, Isfahan University of TechnologyMajid MolkiMechanical Engineering, Southern Illinois UniversityJournal Article19700101A numerical study is carried out to investigate the laminar forced convection heat transfer from a circular cylinder. The fluid is assumed to be incompressible, the Reynolds number ranged from 0.1 to 1000, and the Prandtl number was equal to 0.7. The range of study includes heat transfer in creeping flow (Re40). The equations were discretized by a control-volume-based finite difference technique, and they were solved by the SIMPLE algorithm. The problem formulation is such that it can handle both steady and steady periodic situations. The paper presents the isotherms for the cylinder with isothermal wall and constant wall heat flux. The results indicate that the periodic nature of eddies causes an oscillatory behavior in the heat transfer coefficients. The oscillations are intensified as the Reynolds number is increased.https://www.ije.ir/article_71169_c645e3310f6c9986200008167475eecc.pdfMaterials and Energy Research CenterInternational Journal of Engineering1025-249510119970201A Composite Finite Difference Scheme for Subsonic Transonic Flows (RESEARCH NOTE).374471170ENM. GolafshaniMechanical Engineering, Sharif University of TechnologyNima AmanifardMechanical Engineering, University of GuilanA. HeydariMechanical Engineering, Sharif University of TechnologyJournal Article19700101This paper presents a simple and computationally-efficient algorithm for solving steady two-dimensional subsonic and transonic compressible flow over an airfoil. This work uses an interactive viscous-inviscid solution by incorporating the viscous effects in a thin shear-layer. Boundary-layer approximation reduces the Navier-Stokes equations to a parabolic set of coupled, non-linear partial differential equations. The resulting system of partial differential equations is then solved using an efficient implicit finite difference scheme. A non uniform mesh is used and the eddy viscosity concept models the turbulent Reynolds stress terms. The solution for the steady subsonic and transonic Euler equations is obtained using an upwind finite-volume scheme. The scheme is based on artificial viscosity in the governing equations to provide the necessary dissipation for numerical stability. The system of equations is linearized by a Newton method and the resulting fully coupled system of algebraic equations is solved. Convergence of the method is demonstrated to be robust, taking very few iterations to reach machine accuracy. Shock-Capturing methods extends the applicability of the scheme to situations with shocks. The two schemes are coupled and an iterative procedure is used to link the results of the inviscid and viscous flow fields. Computations are made for a series of flows. Results for NACA 0012 airfoil flows are presented and compared with experimental data and other computational results.https://www.ije.ir/article_71170_b2518b4df85b29f147ef27d8cc2ba0d3.pdfMaterials and Energy Research CenterInternational Journal of Engineering1025-249510119970201Design and Fabrication of a Quartz Crystal Resonator Used in a Thickness-Monitor Unit (TECHNICAL NOTES).454871171ENM. H. Moradli, MercJournal Article19700101This paper deals with the design and fabrication of a quartz-crystal resonator used in a thickness-monitor unit, measuring film thickness in a film-depositing system. A purpose-grown quartz crystal is cut to form the desired wafer. Two gold electrodes are deposited on both surfaces of the wafer to provide electrical contacts. The resonance frequency of the resonator, at room temperature, and the variation of the resonance frequency of the resonator with the temperature are measured. The fabricated resonator is finally used in the thickness-monitor unit of a vacuum coater.https://www.ije.ir/article_71171_9a296f1afcb4e1e68ddb7e4309e21344.pdfMaterials and Energy Research CenterInternational Journal of Engineering1025-249510119970201Preparation Zirconia Toughened Alumina by Deflocculation-Flocculation Route (TECHNICAL NOTE).495471172ENM. Solati-Hashjin, MercJournal Article19700101Partially stabilized zirconia (PSZ) agglomerate toughened alumina has been prepared by the "deflocculation-flocculation" technique, using 2 and 3 mol. % Y2O3-doped zirconia powders. Samples containing up to about 30 vol.% zirconia were obtained. The resulting microstructure seems to be mainly influenced by the physical properties of the starting powders, e.g. agglomerate size and the specific surface area. The mechanical properties, specially the strength of the samples are mainly limited by the flaws entering the microstructure through the differential sintering of the agglomerates relative to the surrounding matrix.https://www.ije.ir/article_71172_e296bec92fc42527cffb676131df6ffc.pdfMaterials and Energy Research CenterInternational Journal of Engineering1025-249510119970201The Study of Thermodynamic Surface and Contact Characteristics by a New Method of Simultaneous Thermooptical Analysis (TECHNICAL NOTES).555971173ENL. Y. OstrovskayaMaterials Engineering, National Academy of Engineering (NAE)Journal Article19700101A device is described for studying thermodynamic and surface characteristics of metals as well as for differential thermal analysis of materials. A promise its shown is application for a multiple examination of high-temperature capillarity in a number of technological processes involving the formation or contribution of a liquid phase.https://www.ije.ir/article_71173_e9a12dcf2fd7f071ff43e778ff9cc36b.pdf